The HPV vaccine not only has resulted in a decrease in human papillomavirus infection in immunized teens but also in teens who were not immunized.

The study is believed to be the first to show a substantial decrease in HPV infection in a community setting as well as herd protection -- a decrease in infection rates among unimmunized individuals that occurs when a critical mass of people in a community is immunized against a contagious disease.

The Cincinnati Children's Hospital Medical Center study will be published online July 9 in the eFirst pages of Pediatrics.